Graft Co-polymerization of Acrylic Acid on Ultrasonic Activated Starch in Inverse Emulsion

The graft co-polymerization of acrylic acid in inverse emulsion on the cassava starch pretreated with ultrasonic activation was studied with Span 80 and OP-10 as the emulsifier, cyclohexane as the oil phase medium and ammonium persulfate as the initiator. The effects of ultrasonic activation time, reaction time, reaction temperature, concentration of initiator, the mass ratio of acrylic monomer to cassava starch, the amount of emulsifier and volume ratio of oil to water on the conversion of acrylic acid, grafting percentage and grafting efficiency were investigated. The results showed that the optimal conditions of reaction correspond to as follow: activation time was 30 min, reaction temperature was 50℃, initiator concentration was 1.59 mmol/L, reaction time was 120min, the mass ratio of starch to acrylic acid was 5.5, the emulsifier content was 6%, the volume ratio of oil to water was 1.2, and the monomer conversion, grafting percentage and grafting efficiency was 96.1%, 81.9% and 85.8%, respectively. Since the crystal structure of cassava starch could be destroyed by ultrasonic activation, the chemical reaction activity of cassava starch was obviously enhanced by the ultrasonic activation, and then the grafting activity of acrylic monomer on starch was also enhanced.